Control mechanism for rotorcraft



2 Sheets-Sheet 1 Filed April 4, 1960 Hans DehszL/nntd Ammo MMQD 9 0-14414,

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CONTROL MECHANISM FOR ROTORCRAFT Filed April 4 1960 2 Sheets-Sheet 2 I 90 J 13 42 21 r 1 2 72 A B IQQHIIHIHHJQIIHlllllkf 37 BVGY: [75* A H4: Der-sch m,

United States Patent Ofilice 3,053,326 Patented Sept. 11, 1962 3,053,326 CUNTROL MECHANESM FOR RQTORCRAFT Hans Derschmidt, Munich, Germany, assignor to Eolkow- Entwicklungen K.G., Munich, Germany Filed Apr. 4, 1960, Ser. No. 19,869 Claims priority, application Germany Apr. 7, 1959 9 Claims. (Cl. 170-16025) The invention relates to the control of a rotorcraft, in which the vertical or height control of the rotorcraft is effected by the axial displacement of a wobble plate on the shaft of the rotor of the rotorcraft by means of a sliding sleeve and through an adjusting lever, whilst the control of the rotorcraft in the various horizontal directions is effected by the appropriate inclination of this wobble plate by means of a pair of rocker arms.

It is already known to design the control linkage for rotorcraft in such a manner that the collective pitch, effected for all rotor blades together, and required for the vertical control of the rotorcraft, and the cyclic pitch effected successively for the individual blades of the rotor, whereby the rotorcraft is steered or controlled in the various horizontal directions, is effected largely by the same linkage components. With known embodiments, the superimposition of these two control movements is effected in that way that at least one lever makes a tilting movement for the horizontal control, and is displaced along its axis for the vertical or height control. From this lever, a suitable linkage leads to the vicinity of the rotor shaft and along the same to a wobble plate mounted on gimbals on the rotor shaft. These linkage guides are usually very complicated and heavy, mainly in view of the fact that, according to the design, shafts may have to be used for the power transmission, and these shafts may have to be very strong in order to provide the required rigidity.

It appeared that the arrangement of the linkage in the vicinity of the rotor shaft obstructs the fitting of other important structural elements. The present invention has the object of eliminating this disadvantage and of simplifying the control linkage.

According to the present invention the cyclic pitch adjusting levers are supported by means of their pivots on the collective pitch adjusting lever actuating the sliding sleeve. The ends of the cyclic pitch adjusting levers engage the wobble plate directly.

According to a preferred embodiment, an intermediate member is used for supporting the pivots of the tilting levers, this intermediate member being pivotably connected to the adjusting lever and to the tilting levers.

It is an essential characteristic of the invention that the linkage for the horizontal control of the rotorcraft comprises at least two linkage systems in mutually symmetrical arrangement. With this arrangement, the pivot of the control column for the horizontal control of the rotorcraft may preferably be located in the plane of symmetry of the symmetrically arranged linkage system. In a similar way, the rotor shaft may be arranged in the plane of symmetry between the two symmetrically arranged linkage systems.

Preferably, the tilting levers are arranged substantially in a first plane, which is perpendicular to the axis of the rotor, and the adjusting lever is arranged substantially in a second plane, located below the first plane and parallel thereto. The intermediate member is substantially parallel to the axis of the rotor.

In a first preferred embodiment of the invention, the tilting levers are in cross-wise arrangement, and are located between the axis of the rotor and the control column for the horizontal control of the rotorcraft.

In a, second preferred embodiment of the invention, these tilting levers are arranged side by side. The axis of the rotor is here located between the tilting levers and the control column for the horizontal control of the rotorcraft.

It is of particular importance for the design of this invention that the control column for the horizontal control of the rotor craft is connected with the shift levers by two rods which are so arranged that they form a certain angle. This angle is equal to the angle formed by the lines connecting the pivoting points of the tilting levers at the horns of the wobble plate with the axis of the rotor.

By means of this arrangement and the symmetrical arrangement of the linkage systems indicated above there results in a linkage, which consists of two series each of symmetrically arranged and identical parts. The manufacture of the linkage is, however, considerably simplified. The simplicity of the symmetrical linkage is apparent particularly in the case of a rotorcraft with twin controls. In this arrangement, with two co-ordinated elements of the linkage, a second control column with two pull-pressure rods may be fitted, Without requiring further linkage components.

Furthermore, the linkage of the invention has the advantage that the space in the vicinity of the axis of the rotor remains free for the motor and the transmission. Since, therefore, the motor, which represents usually the heaviest component of the rotorcraft, may be arranged in the extension of the rotor axis, it is unnecessary to balance the momentum, such as would be required if the weight were located eccentrically.

Further advantages and characteristics will become apparent from the following description in which two preferred embodiments are described with reference to the accompanying drawings, without, however, limiting the present invention in any way to the embodiments described herein.

In the drawings:

FIG. 1 is a view of perspective of the first embodiment applied to a rotorcraft having only one rotor, in which the linkage is arranged between the control column for the horizontal control of the rotorcraft and the rotor shaft;

' FIG. 2 is a section along the line IIII of FIG. 1;

FIG. 3 is a section along the line III-III of FIG. 1; FIG. 4 is a view in perspective of a second embodiment applied to the rotorcraft having two rotors, in

which the rotor shaft is arranged between the control column for the horizontal control of the rotorcraft and the linkage.

Referring to the embodiment of FIG. 1, a control column for controlling the rotorcraft in the various horizontal directions is located in a universal joint 3 which is supported on the frame or fuselage of the rotorcraft. 1 The free end of the control column 1 is connected, by means of a ball and socket joint 2, to two rods 4 and 5 which include the angle 0:. These rods 4- and 5 are pivoted to the shift levers 64 and 65, respectively, the pivots of which are located in fixed points of the fuselage of the aircraft. From these shift levers 6'4 and 65, rods 66 and 6'7 lead to tilting levers 68 and 69, being connected to their free ends by means of joints 68a and 6901.

In the embodiment of FIG. 1, these tilting levers 68 and 69 are in a cross-wise arrangement, that is they may be swivelled, as is shown in FIG. 2, about a common bolt link 70.

On a rotor shaft 47, a sliding sleeve 44 is slidably located in a manner known per se, and supports a wobble plate which is freely tiltable in all directions. This wobble plate consists, as is known per se, of a stationary member 18, that is a member which does not revolve with the rotor shaft 47, and of a part '46 which revolves with the rotor shaft 47. The wobble plate 46 may be tilted in various directions by means of the horns 71 and 72 in that these horns 71 and 72 are connected with the tilting levers 69 and 68, respectively, at the joints 76 and 77. The imaginary lines connecting the joints 76 and 77 with the axis of the rotor shaft 47 include the same angle a as the rods 4 and 5.

The angle a may be an obtuse or an acute angle. For producing favourable kinematic conditions it is expedient that this angle should not deviate much from a right angle.

The sliding sleeve 44 has a projection 85, to which is pivoted at 87 one end of an adjusting lever 88. The other end 84a of this adjusting lever 88 is connected to the rotorcraft fuselage through a guide rod 84. This adjusting lever 88 is actuated by a rod 80, which is pivotable about the pin 83. The rod 80 may be actuated by a control column 30 through a lever 82. This control column 30 serves to control the vertical movement of the rotorcraft, that is, if operated, it causes an axial displacement of the sliding sleeve 44 on the rotor shaft 47.

The pivot pin 70 of the tilting levers 68 and 69 is supported by an intermediate member 86, which is also pivoted to the pin 83 (see also FIG. 3).

To the outer part '46 of the wobble plate, which revolves with the rotor shaft 47, there is fitted an arm 90, Whereby the single rotor blade 92 is adjusted by means of a rod 91; this rotor blade is pivotably located in a rotor head 75. If several rotor blades 92 are used, the wobble plate 46 has, in a manner known per se a corresponding number of projections 90 with further rods 91.

According to the invention, the operation of the control column 30 has only the purpose of causing the axial displacement of the sliding sleeve 44 and of the wobble plate 46, but not the tilting of the latter, whilst the operation of the control column 1 has the purpose of causing only the tilting of the wobble plate '46, but not the axial displacement of the same on the rotor shaft 47. This condition is fulfilled, if the distances between the pivot points 68a and 69a and the bolt or pin 70 are in the same relation to the distance between the pin 70 and the pivots 76 and 77 as the distance between the pivot 84a and the pin 83 to the distance between the pin 83 and the pivot 87.

With the embodiment shown in FIG. 4, the rotor shaft 47 is located between the control column 1 and the linkage. Accordingly, with this embodiment the linkage need not be arranged cross-wise.

, The control column 1 is located in gimbals or in a universal joint in the same manner as disclosed in conjunction with the embodiment of FIG. 1. The rods 4 and 5, which include the angle a, are connected to the ball and socket joint 2 of the control column 1. The movements of the control column 1 are transmitted through the shift levers 6 and 7 to the rods 8 and 9, respectively, and from these through the shift levers 10 and 11, respectively, to the rods 12 and 13. The rods 12 and '13 are located parallel to the shaft 47 of the rotor. If, as shown in the drawing, the motor 101 is directly connected to the shaft 47 of the rotor, the rods 12 and 13 pass to the side of the motor 101.

The free ends 14a and 15a of tilting levers 14 and 15 are pivoted to the rods 12 and 13. Contrary to the arrangement of FIG. 1, in the arrangement of FIG. 4, the tilting levers 14 and 15 are in side-by-side arrangement. The other ends 24 and 25 of the tilting levers 14 and 15 are pivoted to the horns 71 and 72 of the wobble plate 46. The imaginary lines connecting the pivoting points 24 and 25 to the axis of the rotor shaft 47 again include the same angle or. The arms 90 of the wobble plate 46 are connected with the rotor blades 92 by means of rods 91.

The tilting levers 14 and 15 are pivoted to a three-armed intermediate member 19 at 20 and 21, respectively. This intermediate member 19 rests, by means of a pivot pin 50, on a shift lever 49, which may be operated from the control column for the vertical control of the aircraft,

from a revolving shaft 48, through a lever 37, a rod 36, a shift lever 35 and a rod 34. The control column 30 is rotatably located with a shaft 31 at a fixed point of the frame of the aircraft. A projecting angled arm 32 of the control column 30 is pivotably connected at 33 to the rod 34.

The lever 49 engages into a slot 45 of a lever 40 by means of a pin 41. The lever 40 is rotatably connected at 39 to the sliding sleeve 44. The free end 42 of the lever 40 is pivoted to a fixed point of the aircraft frame by means of a link 43 and a rotary shaft 51.

Movement of the control column 1, whilst the control column 30 is held stationary, will cause the wobble plate 46 to be positively inclined in the direction of inclination of the control column 1. If the control column 30 is moved towards the top, with the centrol column 1 held stationary, the adjusting lever 49 is displaced in an upward direction through the shift lever 49 and the shaft 48. During this movement, the auxiliary lever 40 is carried along by the pin 41, so that the sliding sleeve 44, which is located on the rotor shaft 47, also slides in an upward direction together with the wobble plate 46. In order to effect the parallel displacement of the wobble plate without the inclination thereof, the links 24 and 25 must move in an upward direction by the same amount as the wobble plate 46, when the control column 30 is operated. This may be effected by appropriately selecting the lever ratios, in particular in that the distance between the pivot pin 39 and the pin 41 is one half of the distance between the pivot 39 and the free end 42 of the lever 40, and in that the distance between the pin 41 and the pivot 50 is twice as large as the distance between the pivot 39 and the free end 42 of the lever 49. The distance between the axis of rotation of the shaft 48 and the pivot 50 corresponds to the distance between the pivot 39 and the free end 42 of the lever 40. The revolving spindles 20 and 21 of the tilting levers 14 and 15 are located, with the embodiment shown, between the points 24 and 25, respectively, and 14a and 15a respectively.

I claim:

1. In a rotorcraft, a power-driven rotor shaft having attached to its upper end at least one rotor blade journalled for rotation about an axis extending transversely to that of the rotary shaft, a non-rotatable sleeve mounted on the rotor shaft for axial movement thereof, a wobble plate journalled on the sleeve, the wobble plate including a variable inclination member connected to the rotor blade for rotation therewith and a non-rotatable member of variable inclination having extending outwardly from it a pair of fixed arms forming between them at the rotor shaft axis a predetermined angle, a collective pitch adjusting lever being pivotally connected at one end to the sleeve and at the other end to a pivot, a pair of cyclic pitch adjusting levers being each pivotally connected at one end to one of the fixed arms and at the other end to the upper end of one of a pair of link members extending in parallel with the rotor shaft axis, the lower ends of the link members being pivotally connected to a cyclic pitch control column through a pair of connecting arms forming between them an angle equal to the predetermined angle by means whereby movement of the cyclic pitch control colurrm is translated into axial movement of at least one of the link members and thereby variation in the angle of inclination of the wobble plate, each of the pitch adjusting levers having a fulcrum intermediate its ends, all of the fulcra being rigidly secured to each other, and the fulcrum of the collective pitch adjusting lever being connected to a collective pitch control column by means whereby movement of the collective pitch control column is translated into axial movement of the sleeve.

2. The combination as claimed in claim 1, in which the fulcra of the pitch adjusting levers are pivotally connected to the ends of a rigid intermediate member.

3. In a rotor craft, a power-driven rotor shaft having attached to its upper end at least one rotor blade journalled for rotation about an axis extending transversely to that of the rotary shaft, 21 non-rotatable sleeve mounted on the rotor shaft for axial movement thereof, a wobble plate journalled on the sleeve, the wobble plate including a variable inclination member connected to the rotor blade for rotation therewith and a non-rotatable member of variable inclination having extending outwardly from it a pair of fixed arms forming between them at the rotor shaft axis a predetermined angle, a collective pitch adjusting lever being pivotally connected at one end to the sleeve and at the other end to a pivot, the collective pitch adjusting lever extending substantially perpendicularly to the rotor shaft axis, a pair of cyclic pitch adjusting levers being each pivotally connected at one end to one of the fixed arms and at the other end to the upper end of one of a pair of link members extending in parallel with the rotor shaft axis, the pair of cyclic pitch adjusting levers being located in a plane extending substantially perpendicularly to the rotor shaft axis, the lower ends of the link members being pivotally connected to a cyclic pitch control column through a pair of connecting arms forming between them an angle equal to the predetermined angle by means whereby movement of the cyclic pitch control column is translated into axial movement of at least one of the link members and thereby variation in the angle of inclination of the wobble plate, each of the pitch adjusting levers having a fulcrum intermediate its ends, all of the fulcra being pivotally connected to the ends of a rigid intermediate member extending substantially in parallel with the rotor shaft axis, the fulcrum of the collective pitch adjusting lever being connected to a collective pitch control column by means whereby movement of the collective pitch control column is translated into axial movement of the sleeve.

4. The combination as claimed in claim 1, in which the fulcrum of the collective pitch adjusting lever is pivotally connected to the upper end of a link member extending in parallel with the rotor shaft axis, the lower end of which is connected to the collective pitch control column.

5. The combination as claimed in claim 1, in which the pivotal connections of the pair of fixed arms extending from the wobble plate to the cyclic pitch adjusting levers, and the pivotal connection of the sleeve to the collective pitch adjusting lever, lie in a plane extending in parallel with the rotor shaft axis.

16. In a rotorcraft, a power-driven rotor shaft having attached to its upper end at least one rotor blade journalled for rotation about an axis extending transversely to that of the rotary shaft, a non-rotatable sleeve mounted on the rotor shaft for axial movement thereof, a wobble plate journalled on the sleeve, the wobble plate including a variable inclination member connected to the rotor blade for rotation therewith and a non-rotatable member of variable inclination having extending outwardly from it a pair of fixed arms forming between them at the rotor shaft axis a predetermined angle, a collective pitch adjusting lever being pivotally connected at one end to the sleeve and at the other end to a pivot, a pair of cyclic pitch adjusting levers being each pivotally connected at one end to one of the fixed arms and at the other end to the upper end of one of a pair of link members extending in parallel with the rotor shaft axis, the pair of cyclic pitch adjusting levers having a common fulcrum, the lower ends of the link members being pivotally connected to a cyclic pitch control column through a pair of connecting arms forming between them an augle equal to the predetermined angle, the cyclic pitch control column being arranged on the opposite side of the common fulcrum from the rotor shaft, whereby movement of the cyclic pitch control column is translated into axial movement of at least one of the link members and thereby variation in the angle of inclination of the wobble plate, each of the pitch adjusting levers having a fulcrum intermediate its ends, all of the fulcra being rigidly secured to each other, and the fulcrum of the collective pitch adjusting lever being connected to a collective pitch control column by means whereby movement of the collective pitch control column is translated into axial movement of the sleeve.

7. A combination as claimed in claim 6, in which the fixed arms extending from the wobble plate, the cyclic pitch adjusting levers, the pair of link members and the pair of connecting arms to the cyclic pitch control column are symmetrical about a plane containing the rotor shaft axis and the pivot of the cyclic pitch control column.

8. In a rotorcraft, a power-driven rotor shaft having attached to its upper end at least one rotor blade journalled for rotation about an axis extending transversely to that of the rotary shaft, 3. non-rotatable sleeve mounted on the rotor shaft for axial movement thereof, a wobble plate journalled on the sleeve, the wobble plate including a variable inclination member connected to t e rotor blade for rotation therewith and a non-rotatable member of variable inclination having extending outwardly from it a pair of fixed arms forming between them at the rotor shaft axis a predetermined angle, a collective pitch adjusting lever being pivotally connected at one end to the sleeve and at the other end to a pivot, a pair of cyclic pitch adjusting levers being each pivotally connected at one end to one of the fixed arms and at the other end to the upper end of one of a pair of link members extending in parallel with the rotor shaft axis, the pair of levers extending in parallel with each other, the lower ends of the link members being pivotally connected to a cyclic pitch control column through a pair of contacting arms forming between them an angle equal to the predetermined angle, the cyclic pitch control column being on that side of the rotor shaft which is opposite to the pair of levers whereby movement of the cyclic pitch control column is translated into axial movement of at least one of the link member and thereby variation in the angle of inclination of the wobble plate, each of the pitch adjusting levers having a fulcrum intermediate its ends, all of the fulcra being rigidly secured to each other, and the fulcrum of the collective pitch adjusting lever being connected to a collective pitch control column by means whereby movement of the collective pitch control column is translated into axial movement of the sleeve,

9. A combination as claimed in claim 8, in which the fixed arms extending from the wobble plate, the cyclic pitch adjusting levers, the pair of link members and the pair of connecting arms to the cyclic pitch control column are symmetrical about a plane containing the rotor shaft axis and the pivot of the cyclic pitch control column.

References Cited in the file of this patent UNITED STATES PATENTS 2,445,550 Wotton July 20, 1948 2,627,929 Sikorsky Feb. 10, 1953 2,698,059 Pullin Dec. 28, 1954 2,934,152 Davenhaver Apr. 26, 1960 

